Fabrication of porous carbon nanotube network

We used the spin-coating method combined with ultrasonic atomization as a continuous, one-step process to generate a two-dimensional honeycomb network that was constructed from pure multi-walled carbon nanotubes

Soft X-ray resonant scattering study of single-crystal LaSr2_2Mn2_2O7_7

Soft X-ray resonant scattering studies at the Mn $L_{\texttt{II, III}}$- and the La $M_{\texttt{IV, V}}$- edges of single-crystal LaSr$_2$Mn$_2$O$_7$ are reported. At low temperatures, below $T_\texttt{N} \approx 160$ K, energy scans with a fixed momentum transfer at the \emph{A}-type antiferromagnetic (0 0 1) reflection around the Mn $L_{\texttt{II, III}}$-edges with incident linear $\sigma$ and $\pi$ polarizations show strong resonant enhancements. The splitting of the energy spectra around the Mn $L_{\texttt{II, III}}$-edges may indicate the presence of a mixed valence state, e.g., Mn$^{3+}$/Mn$^{4+}$. The relative intensities of the resonance and the clear shoulder-feature as well as the strong incident $\sigma$ and $\pi$ polarization dependences strongly indicate its complex electronic origin. Unexpected enhancement of the charge Bragg (0 0 2) reflection at the La $M_{\texttt{IV, V}}$-edges with $\sigma$ polarization has been observed up to 300 K, with an anomaly appearing around the orbital-ordering transition temperature, $T_{\texttt{OO}} \approx 220$ K, suggesting a strong coupling (competition) between them.Comment: Accepted by European Physical Journal

The effects of the composition of microporous layers on the permeability of gas diffusion layers used in polymer electrolyte fuel cells

The effects of the composition of the microporous layer (MPL) on the through-plane permeability of the gas diffusion layers (GDLs) used in polymer electrolyte fuel cells (PEFCs) have been thoroughly experimentally investigated in this paper. For a given PTFE loading in the MPL, the GDL permeability was found to decrease with increasing carbon loading and this is due to the increase in the thickness of the MPL. For all the investigated carbon loadings of the MPL, the permeability values of the GDLs were found to have common trends for the PTFE loadings ranging from 10 to 50% (by weight): the GDL permeability increases when the PTFE loading in the MPL is increased from 20 to 50%; the GDL permeability decreases when the PTFE loading in the MPL is increased from 10 to 20%; and the GDL permeability is a minimum at 20% PTFE loading present in the MPL. On the other hand, the permeability of the GDL was found to depend on the carbon loading of the MPL in the PTFE range 0–10%. The effects of the MPL composition on the MPL permeability were found to be similar to those on the GDL permeability. However, the permeability values of the MPLs of the same composition, which were supposed to be ideally the same, were found to significantly vary. This was attributed to the MPL penetration into the body of the carbon substrates

The application of a novel fluidised photo reactor under UV-Visible and natural solar irradiation in the photocatalytic generation of hydrogen.

With advancements in the development of visible light responsive catalysts for H2 production frequently being reported, photocatalytic water splitting has become an attractive method as a potential 'solar fuel generator'. The development of novel photo reactors which can enhance the potential of such catalyst, however, is rarely reported. This is particularly important as many reactor configurations are mass transport limited, which in turn limits the efficiency of more effective photocatalysts in larger scale applications. This paper describes the performance of a novel fluidised photo reactor for the production of H2 over two catalysts under UV-Visible light and natural solar illumination. Catalysts Pt-C3N4 and NaTaO3·La were dispersed in the reactor and the rate of H2 was determined by GC-TCD analysis of the gas headspace. The unit was an annular reactor constructed from stainless steel 316 and quartz glass with a propeller located in the base to control fluidisation of powder catalysts. Reactor properties such as propeller rotational speed were found to enhance the photo activity of the system through the elimination of mass transport limitations and increasing light penetration. The optimum conditions for H2 evolution were found to be a propeller rotational speed of 1035rpm and 144W of UV-Visible irradiation, which produced a rate of 89μmol h-1 g-1 over Pt-C3N4. Solar irradiation was provided by the George Ellery Hale Solar Telescope, located at the California Institute of Technology